A myriad of biomarkers containing aldehyde and ketone moieties exist and can play an important role in the biological, forensic, medical and industrial sciences. In particular, aldehydes and ketones are known to be key end products in the degradation of a variety of biological molecules, such as, lipids, nucleic acids, carbohydrates and proteins. In a number of instances, these end products are a result of oxidative stress.
A number of reagents for the detection of aldehyde and ketone-containing moieties have been proposed, however, each with limited success. Among the most widely used of such reagents are dansyl hydrazine, fluorescein thiosemicarbazide, various biotin hydrazides, biotin hydroxylamine (ARP), and various aromatic amines (such as 2-aminopyridine, 8-aminonaphthalene-1,3,6-disulfonic acid, 1-aminopyrene-3,6,8-trisulfonic acid, 2-aminoacridone, and 8-amino-1,3,6-pyrene trisulfonic acid (APTS)). Unfortunately, use of these reagents requires additional purification and/or secondary reagents.
Existing methods of labeling carbohydrates that utilize hydrazine, hydroxylamine and amine derivatization reagents have focused on labeling aldehydes present in, or introduced into, carbohydrates, particularly the so-called “reducing sugars”. Aldehydes are typically introduced into carbohydrates by periodate oxidation. The adduct formed with the reducing sugar typically needs to be stabilized by treatment with borohydride or cyanoborohydride, both of which are toxic materials and present hazards to the user and for disposal. The derivatization reaction typically precedes or is followed by a separation technique such as chromatography, electrophoresis, precipitation, affinity isolation or other means before direct or indirect detection of the labeled product. Therefore, there is a need for reagents that permit rapid in situ detection of aldehyde and ketone moieties upon contact and that do not require reductive amination in order to stabilize the adduct.